The present invention relates generally to welding-type apparatus and, more particularly, to a welding-type apparatus configured to deliver a variable hot start. The welding-type device determines a configuration of the welding-type device and a plurality of output parameters, selects a startup welding-type output according to the configuration and output parameters, and dynamically adjusts the startup welding-type output over a hot start period.
One common type of welding-type process is a stick or shielded metal arc welding (SMAW) process. During this process an electrode (stick/rod) comprising a wire core covered with a flux coating is used to deliver a welding arc. For a given SMAW process, it is desirable to control the power supply output to provide a desired voltage/amperage (V/A) curve. Typically, the desired power supply output V/A curve includes a substantially constant current portion within a typical operating voltage range and a “droop” portion where current decreases as voltage increases. Additionally, many welding-type devices provide a “dig” portion where the current increases as voltage decreases for a lower than normal operational voltage range. Thus, it is desirable to provide a power supply that has a constant current portion of the output V/A curve within a typical welding-type voltage range and variable current outputs outside the typical welding-type voltage range.
To initiate an SMAW welding-type process, some welding-type devices provide a “boosted” output, called a hot start. Traditionally, the boosted output includes a fixed amplitude and duration. However, experienced operators typically require less power to initiate an arc than do inexperienced operators. As such, some hot starts could be too “hot” for experienced operators and/or not hot enough for inexperienced operators. If the hot start is too hot, the operator could “blow through” a workpiece. On the other hand, if the hot start is not hot enough, the operator may need to repeatedly attempt to initiate an arc which may mark or scar the workpiece.
Accordingly, modified hot starts have been designed. These systems provide a hot start output similar to the previously described “dig” portion of the V/A output curve. Specifically, if the output voltage drops significantly during the modified hot start period, then an additional boost of current is provided. As such, a voltage drop, such as may occur during a hot start controlled by an inexperienced operator, is responded to with a current increase to initiate an arc. On the other hand, when the voltage remains within a standard range, a constant current is provided until the expiration of the hot start duration.
While such modified hot start systems aid in compensating for variances in operator skill and experience, these hot start systems may still be hampered by operator error. For example, an operator working with an unfamiliar workpiece material, may stray too far into the dig portion of the V/A output curve or remain within the dig portion too long. Accordingly, workpiece “blow through” or scarring may still occur.
Additionally, while such modified hot start systems may compensate for variances in operator skill and experience, these systems do not consider the wide variety of welding-type devices and parameters that may be adjusted. As such, even if operator error does not affect the hot start process, an undesired condition may occur because the hot start process was not adjusted for changes in polarity, electrodes, or other operating parameters.
For example, engine driven welding-type devices may be less responsive than welding-type devices that are powered by static power sources. Accordingly, a hot start process designed for a static power welding-type device may be insufficient for an engine driven welding-type device. Specifically, the duration of the hot start process may necessitate extension in order to adequately start the desired welding-type process. However, by extending the duration of the hot start process, the opportunity for blowthrough, scarring, or other undesirable conditions is also extended.
It would therefore be desirable to have a system and method capable of providing a hot start that would lower the potential for operator error during the hot start period. Additionally, it would advantageous to have a system and method capable of providing a hot start that adjusts to operating parameters of the welding-type device.